Unpublished research using Canadian data has reportedly found that individuals who received the seasonal flu vaccine last year are twice as likely to catch H1N1. The CDC has stated that it has not had similar findings in the US.

WHO stated that regulatory authorities have licensed H1N1 vaccines in Australia, China, Hungary and the United States. Japan and several European countries will soon license vaccines.

WHO reported that drug makers can only produce enough H1N1 vaccine each year for half the planet because they lack factory capacity.

Researchers have reported that the injectable H1N1 vaccine is twice as protective as the inhaled nasal spray version of the vaccine.